The general purpose of the proposed research is to identify and characterize some of the effector substances released into culture media by activated cells. Cells producing such substances include sensitized T lymphocytes stimulated by specific antigen or nonspecific mitogens, B lymphocytes stimulated by certain mitogens, and non-lymphoid cells infected with certain viruses. We will continue studies designed to identify new mediator substances (lymphokines), for example materials chemotactic for basophils, and will delineate the total number of lymphokines which are capable of generation by mitogen-activated, non- sensitized B lymphocytes. We will extend virus studies by using an oncogenic virus, SV40, and comparing the production of lymphokine-like factors in transformed, versus infected but non-transformed cell cultures. Characterization of a crude rabbit anti-guinea pig "lymphokine" antiserum will be continued with the aim of delineating its overall biologic activity in in vitro and in vivo systems, followed by an attempt to prepare monospecific antisera to one or more of the lymphokines, for example MIF. These reagents will be useful both in the studies outlined above, and in attempts to localize cellular sites of lymphokine production.